<!DOCTYPE html>
<html lang="en">

  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>父子通信 demo</title>
  </head>

  <body>
    <div id="app"></div>
  </body>

</html>
<script src="https://cdn.jsdelivr.net/npm/vue@2.7.16/dist/vue.js"></script>
<script src='./index.js'></script>
